Does Mobil1 really protect to 400degF??

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97
Location
NYC
I was reading the back of the Mobil1 0w-40, and it states that it "protects to 400F" [Eek!] . How true is this? Why is everyone so worried about oil temps in the 280-300 range?? [Confused] -Mike P
 
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2,480
Most likely, yes...it will protect at this temp.. This would mean then that temps. of 280-300 are a big deal. However, I believe there are local spikes of temperature that are much higher than this...especially when shutting the car off during extreme heat with no oil or coolant circulating.
 
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8,756
Location
RI
What temperatures do the bearings melt? Your engine is toast before the average oil temp hits 400F.
 
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2,095
Location
IL
quote:
Originally posted by Tyrolkid: ...How true is this? Why is everyone so worried about oil temps in the 280-300 range?? [Confused]
Because all oil thins with temperature. About every 30F the oil thins enough that it would be equivalent to you running the next thinner grade. So if your normal OT is 200F and you run 30wt oil. At 290F you oil will be about as thin as if you were running a 5wt! Protect is a bad choice of words because it will protect much less because it has thinned significantly. They just mean that it won't all volatize off and coke up severely. By the way, before supersyn, they used to say up to 475F. FWIW.
 
Messages
115
Location
Wisconsin
Actually, some locations within the engine will exceed 400°F. The following is a table from a paper by Roy Howell, Chief Chemist, Redline Synthetic Oil Company, Formerly of Lubrisol:
code:
 
Engine Temperature Chart (F) 
Upper Cylinder Wall		 300 -  500
Exhaust Valve			1200 - 1500
Piston Crown			 700 -  800
Hydraulic Valve Lifter		 250 -  300
Crankcase			 200 -  300
Top Ring			 300 -  650
Exhaust Gases			 500 - 1000
Combustion Chamber		3000 - 5000
Coolant Jacket			 165 -  230
Connecting Rod Bearings		 200 -  375
Main Bearings			 200 -  350

 

 
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